Method oe and appaeattjs fob



INVENTOR Q W ATTORNEY Patented Aug. 14, 1928.

UNITED STATES HENBY J'. STEHLI, OF CEDAR GBOVE, NEW JEBSEY.

METHon OF AND AePARA'rUs FOR SINTERING.

` r Application filed November 19, 1926. Serial No. 149337.

My invention relates to the treatment of materials for sintering them and for obtaining gases therefrom, such as materials containing a combustible element in themselves, or materials in which a combustible element may have been mixed, and whose nature is such that when .the combustible element has been ignted the combustion may be carried on by means of a blast of air or other suitable gas for causing the particles to be sintered together 'and to form an agglomerated mass for subsequent treatment in metallurgical or other furnaces; An ex ampleof an orecontaining its combustible element in combnation is a sulphide concentrate of Copper, lead or Zinc, and an example of material to which the eombustible element has been added is a magnetite iron c0ncen-` trate with coke screenings mixed therewith.

In well known forms oi' sintering machines a down-draft through'the ignted materials has been eaused by anexhaust fan for drawing the combustion supporting air through the bed after the material has been ignited. There are numerous disadvantages incident tothe use of such sintering machines tor different purposes, among which are low mechanical efliciency ot an exhaust fan, particu-` larly when Operating under high Vacuum required to draw' air through a bed of`fine ore and the relatively low vaouum obtainable with an cxhaust'rt'anflrapid wear of` the impellersot` such'exhaust 'fans because of the abrasive dust carried through by the gases which strike the mpellerbladesat a relatively high velocity causing a sort of sandblasting action on the impellers,` increasing the cost of maintenance; and the Volumes of the hot gases to be handled are much greater than they would be in case the same amount of gases were handled in a'cold condition In the case of sulpliide ores it is desirable to utilize the sulphur `'and 'the gases `therefrom for the purpose of making sulphuric aoid, and where air' is drawnthrough the bed of material by means of a vacuum 'leakages that oceur in'the fan `casing, in the connections between 'the fan* and the vacuum boxes of the sintering machine, and between the vacuum boxes and theore carriers permits air to be drawn in which dlutes the strength of the gases, frequently to'such an extent asto make the, gases unsutable for the manufaeture of acid .by any of the commercial acid-making processes. Saidgases are also diluted by the combustible gases from the' igniter burner which have been drawn through the bed of material by the fan to eliect an ignition 'of the ore to be sintered. In the treatment of some materials containing sulphates, such, for instance, as iron pyrites residue, the gases given off contain sulphuric anhydride, and as these pyrites frequently are wet the temperature of the gases falls below their condensation point of sulphuric acid and the acd contained in the gases' condenses and rapidly attacks the fan impellers.

The nature 'of the exhaust fan handling dusty gases is such as to require very liberal clearance between the rotating impeller and the housing in which it runs. When operating ata low vacuum the eflioiency of such fan is :tairly good, but the higher the vacuum to be produced the greater the slippage of air becomes due to the large clearances, and hence when Operating at high vacuums the mechancal efliciency of the fan is exceedingly low. It has been proposed to overcome the diflieultyof limitng the vacuum obtainable by the use ot' positive blowers Operating as' exhausters, but even with the ?most thorough cleaning of the gases the amount of dust carried into the exhausters is such as to rapidly fill up the very small clearances and cause injury to or destruction of the blo'wer. 'A further disadvantage of using exhaust fans is that though a given size fan perating at a given speed will set up a certain vacuum, yet if the resistance of the bed of material in the sintering machine offers a greater resist-ance to the air than the vacuum the fan sets up practically no air 'will be drawn through the bed and at all times' the amount of 'air passing through the bed depends entirely upon the resistance of the bed.

` Objects of myf invention are to ignite combustible materials in a` bed of moving material to be sintered and to carry off the products of combustion from the igniter be- 'ore the materials are subjected to the sintering process to prevent such products of combustion from* becoming mingled with gases from the sintering operation; to cause combustion of the materials for sntering at :a location remote from the igniton burn er; to force air orother gases downwardly through the'bed of burning material for sintering it in such a way as to prevent dilntion of the eombustible products on the sinter bed with exeess of air or false air, and

to carry out the sintering operationwithin a closed chamber from which the external atnosphere is excluded.

My invention conprises novel details oi? improvement and combinations of parts hereinat-ter set forth and then nore fully pointed out in the clains.

Reference is to be had to the accompanying drawings, forming a part hereof,Where-.

Fig. 1 is a side elevation, partly in'section, of a sinterng machine embodying my in- Vention;

Fig. 2 is an enlarged cross section substantially on the' plane of line 2, 2, in Fig. l;

Fig 3 isa section on line 3, 3, in Fig.

Fig. 4 is an enlarged cross section substantially on theplane of line l, l in Fig. 1.

Similar nunerals oi: reference indicate corresponding parts in the several views.

The numeral 1 indicates the main frame of a. sintering machine which may be o f any usual or desired constriiction provided with upper substantially horizontally disposed spaced tracks 2 and. lower spaccd t'acks 3, shown inclined downwardly :from the deli 'very end of the machine toward the charging end of the machine, said traclzs being connected by curved portions i, 5 at the opposite ends of the france, the latter being provided With a curved'track 6 adjacent to the track portion 4 at theidelivery end ot the machine. A drive sprocket 7 is journaled in the machine at 8 to be driven in any desired wa-y to operate receptacles or pallets 9 which have wheels or rollers 10 totravel along the tracks,ithe sprocket 7 being adapted to operate the receptacles for pushing them suecessively into enga 'ement with one another along 'the upper tracks 2. A hopper 11 is Secured upon the treme above the receptacles at the charging end ot the machine, whereby the material 12 to be treated or sintcred may be charged into the reeeptacles to rest upon the grate bars 9' or other base of the receptacles. The forcgoing parts may beot' any well known eonstruction in sinterng machines.

I .At13is indi-ca ted an igniter of any desired, variety, such as a burner, or one adapted 'for 'burning charcoal, coke, gas, oil or the like 'for igni ting. the material 12. -On the under side of the receptacles opposite; or below the igniter is a wind box or' chamber M adapted to fit closely along the sides of' the movng receptacles or pal lets 9, which wind box is shown connected to an exhaustpipe 15 which may be connected to any suitable exhaust or vacuun apparatus, suchas a suction fan or blower 15 fordrawing atmospheric air through 'the inaterial 1:2 to support combustion of the ign-ited material. Dead pl'atesl and 17 are Secured to' frame l on opposite sides of the upper 1,eso,345

open end of wind 'box 14, over which dead plates the lower flat sui-'faces 9 of the receptacles slide to exclude air. As the receptacles travel, toward the left in Fg. l, the

outletpipe'or passage :tor gases and the' like. Une end ot the wind box is attached to the dead plate 17 and the'other end is attached to a dead plate 21 at the opposite end ot the wind box, over which dead plate the receptacles travel or slide to exclude ail: thereat 'from the wind box. Above the wind box 20 is another arbox 22, beneath which the charged receptacles travel. The upper air box 22 is connected tightly with the dead plate 18 and at its opposite end box 22 is connected with another dead plate 23 that is shown located over the dead plate 21, s o that as the charged receptacles travel under the deadplates 18 and 23 air will be excluded :from entering box 22. i The respective upper edges of the wind box l9 and the lower edges of the box 22 are so spaced that the charged pallets may pass therebetween. The two boxes 19 and 20 together form a chamber A through which the charged receptacles travel. The`upper portion ot said chamber is supplied with air or other gases under pressure through an inlet pipe at 24, 'which may be forced into the chamber by n'eans' of any suitable blowing device, indicated at 25. The air or gases may be heated in the passage to the box 22 by any suitable means, such as indicated at 26, in the nature ot a heating chambcr. i

When the air or gas is forced into the box22 it will be forced 'through the burning material 12 on the receptacles, (within the chamber A), into the box 1 9, whence it will pass through the outlet pipe 20, thereby causing 'combustion of the materials for sintering the same. The engagement of the dead plates 17 ,i 18, 21 and 23 with thereceptacles- 9, and appropriately the dead plates l8 and 23 with the material 12 on the receptaeles, resists ,the outfiow ofar 01' gases under pressure from the chamber A.

;The gases' and products of combustion caused by the burning of the material 12 within chamber e A, the combustion 'being supported by the flow of air or gases through the material, will be undiluted from any products of eombustion from the igniter 13, which will previously have been drawn off through the wind box 14.' i

In order to resist leakage ofair ox' gases (that are: forced into 'ehamber A) from between the receptacles or pallets' 9 and the box 22' I provide flexible material 27 de pending from the upper wind box 22 into llU 1 1,es o,345

form of any suitable flexible strips which are relatvely soft and of such character as to resist the flow of air and at the same time bear flexibly against the adjacent sealing surfaces' of the receptacles or pallets, such as of henp or asbestos cloth preterably impregnated with' lubricating substanccs, such as graphite or similar material, the strips thereby being made self-lubricating, and which will not wear the metal of the receptacles and is cheap and easy to replace when worn. The strips 27 may be Secured to the lower portion of wind box 22 by any suitable means, such as by rivets or screws at 28, so as to be replaceable. The pressure within the box 22 Will cause the flexible strips 27 to be forced against the side walls of the receptacles above the material or charge 12 therein as the receptacles travel. Also, flexible strips 29 of the character set ,forth regarding, the strips 27 are Secured to the upper portion of the Wind box 19 and below the receptacles, as by means of screws or rivets 30, whereby the strips may be readily replaced. The lower po'tions of the receptacles 9, on opposite sides, are provided with smooth longitudinal surfaces at 9 against which the outer upper surfaces of the fiexible strips 29 are adapted to bear, particularly when forced against said surfaces by pressure from within the chamber A. The nature of the strips 27 and 29 and their functions are substantially the same as respects the flexible strips 16 in cooperation with the receptacles and wind boxes, as set forth in Letters Patent No. l,491,77 8, granted to me April 22, 1924, in the present instance the strips resisting outward air or gas pressure from within the chamber A.

A great advantage of my improvement is that by means of the'fiexible strips 27 and 29 hearing against the travelng receptacles 9 desired pressure of air or gases within chamber A may be maintained with relatively small leakage of said air or gases from the chamber to atmosphere, and a further advantage is attained by reason of forcing air or gases into chamber A and through the bed ot' material 12 upon the receptacles' so that leakage of false air into the chamber is obviated, which would tend to dilute the gases and products of conbustion passing from the material 12 being sintered in chamber A.

Having now described my invention what I claim is e 1. A sintering machine comprising means to support and operate movable receptacles, an ignter for igniting combustible material on the receptacles, a 'wind box in position to receive products of combustion from the igniter draWn throughsaid material, means to induce suction through the wind box, a substantially closed chamber spaced from the igniter having means to permit the travel of the charged receptacles therethrough, and means independent of said suction inducing means for blowing air or other gases free from initial combustion products from the igniter through said chamber for passage through the material on the receptacles.

2. Theimethod of treating 'material cont aining a combustible element consisting in applyin'g ignited combustible gases to said element to ignite it to generate heat within said material, conducting from said material the produots of combustion from the ignited combustible gases, passing the ignited material through a closed chamber, blowing combustion supporting gases free from products of the ignited combustible gases, into the upper portion of the chamber and into the ignited material and forcing the products of combustion into the lower portion ofthe chamber, and conducting away the products of oombustion from the chamber.

i HENRY J. STEHLI. 

